I went with the 440/493 combo in my 63 but I wanted to use the RB block in case I ever decide to go with the factory crossram. And I knew I was not going to make more then 650 hp. Many feel your pushing your luck to run an RB block when going over 650 to 700 hp and as you know the low deck is a bit stronger. Also I don't race my car alot as it would make a difference to me if my car was getting raced every weekend. You just have to weigh out what you have and what will work best. Either should be fine for what you want. Good luck with it. Ron